Portable fans are employed for a variety of purposes including air circulation and convective cooling. Portable fans are relatively small and light, and are intended to be placed on the floor or on a countertop. The most frequently used forms of portable fans are the box fan and the pedestal fan which have an axial flow fan contained within an enclosure which is placed on the floor or mounted atop a pedestal, respectively.
Many improvements have been included in the design of portable fans to optimize or enhance their performance as coolers and air circulators. Specifically, improvements have been made in controlling the volume and direction of airflow to suit the purpose for which the fan is employed.
To enhance the convective cooling ability of fans, different ways of directing the air-stream generated by a fan towards a particular target have been developed. For example, fan enclosures have been pivotally mounted atop a pedestal so that the fan can be angularly rotated about the vertical axis to adjust the direction of the airflow in the horizontal plane. To adjust the vertical elevation of the airflow, fans have been rotatably mounted to a U-shaped base forming a yoke-like structure, thereby allowing the fan to be adjusted so that the airflow is directed at a specific target in the vertical plane. These two adjustment configurations, in combination, allow the air-stream generated by a fan to be directed toward any target within a room regardless of where the base of the fan is located.
Another use of portable fans is general air circulation. Directed airflow may cool one target, but may not generally reduce or equilibrate the temperature of a room. This latter problem further persists in part due to the stratification of the air temperature in a room. To break up the stratification of the air in a room, a floor circulator can be employed to vertically direct the air flow from the fan to create turbulence within a room and break down the stratification.
U.S. Pat. No. 2,667,301 demonstrates the complementary nature of air circulation and convective cooling. This patent discloses a fan mounted to a base unit which allows the vertical direction of the generated airflow to be altered by rotating the fan about a horizontal mounting axis. The fan further includes legs on the front face of the fan that allow the fan to be placed flat against the floor to circulate room air by creating turbulent vertical flow.